Live television broadcasting typically involves capturing media content from a live scene (e.g., a sports venue, news broadcast, etc.), transmitting the captured content to a remote production facility where the video and audio signals are managed by production switchers, and then encoding the signals for transport to a distribution network. Each step in this process involves a certain level of delay, which, as a result, means that live television broadcasts today are far from being actually “live” or in “real-time”. For example, typical transmission delay times can range from a few seconds to tens of seconds, which is the time delay between when media content is captured to when a program is transmitted and ultimately viewed by the end consumer. Moreover, this delay can be variable. For example, if an end consumer watches the same program on a tablet, there will be a different delay than if the consumer watches it on a monitor fed by an set-top box (“STB”), or yet different again from a monitor fed by an over-the-air signal using ATSC (“Advanced Television Systems Committee”) transmission, as one example.
FIG. 1 illustrates a block diagram of a conventional system for producing a live television broadcast. As shown, the system can include a plurality of cameras 21A and 21B (two cameras are shown, but there can be multiple media streams generated by cameras) that capture media content from a venue 10 (e.g., a sports venue) and provide media streams 22A and 22B to a local encoder 30. The encoder 30 in turn encodes the media streams and provides the media as contribution feeds to a remote production facility 31 using satellite communication, for example. The production facility 31 will typically include video production equipment 11 that can be composed of production switches, controllers, processors, timing modules, a codec, and other equipment provided to process the incoming media streams for a television broadcast production. Furthermore, a technical director 12 can be located at the remote production facility 31 to control the video switcher(s) and make editorial and artistic decisions for the video production.
One significant technical problem with this arrangement is limited available bandwidth at venues to transmit the contribution feeds to the remote production facility. For example, at many venues, the available bandwidth may only be 1 GbE, for example. As a result, broadcast production will necessarily be limited to a minimum number of media streams that can provided by cameras 21A and 22B and may even be limited in the resolution of the video production that can be transmitted to the facility. For example, encoded high definition (HD) signals may consume too much bandwidth and create unacceptable latency periods. Accordingly, the broadcast system shown in FIG. 1 is quite limited in video production capabilities for live broadcast and cannot handle many cameras and/or incoming media streams.
FIG. 2 illustrates a block diagram of another system for producing a conventional live television broadcast. Quite simply, for a large event like the Super Bowl or the Olympics, a television network may move both the video production equipment 11 and technical director 12 to the location of the venue 10 using a production truck 10, for example. However, this arrangement is also not ideal from a live video production perspective. For example, it is difficult and costly to move a large portion of the production crew including the technical director 12 to the venue. Moreover, the technical director 12 may have difficulty within the small confines of the truck 10 viewing the many media streams from the various cameras and manage/control the video switcher accordingly.
In either conventional system, the technical director 12 will typically operate the video switcher (and associated devices) and also serve as the chief of the production crew. Using the video switcher, the technical director 12 will switch video sources and also perform live digital effects and transitions, and insert prerecorded material, graphics and titles. In live video broadcast productions, the technical director 12 must coordinate the production and make rapid decisions. Thus, referring back to the configuration shown in FIG. 1, if the technical director 12 is located in a production control room of the remote production facility 31, the technical director 12 will often issue control decisions 32 that are fed back to cameras 21A and/or 21B to adjust the capture of media content, such as shading, video capture angles, etc. However, this control process creates further time delay in the video broadcast.
Specifically, FIG. 3 illustrates a timing diagram of a conventional system for producing a live television broadcast. Time is shown along the X axis with the starting point in time being the real time event, which would be from a perspective of a person actually attending the sporting event at the venue 10, for example. Albeit small, there will even be a first delay T1 from when light is captured by the camera lens and the pixel data is output. Moreover, as further shown, there are delays at each stage of the process. For example, there is a second delay T2 from the camera(s) to the encoder 30 and a third delay T3 when the signal is decoded at the remote production facility 31 before each media stream can be presented to the technical director after a fourth delay T4. Although each delay is shown as being identical, it should be appreciated that the delays will vary according to bandwidth constraints and other propagation delays, such as device processing, conductor impedance of network links, and the like.
As described above, the technical director 12 can then operate the video switcher to issue control commands back to the local equipment (e.g., cameras 21A and 21B) at the venue 10. However, these command signals will also experience an effective delay Tcontrol when they are fed back to the devices. As further shown, each subsequent step of production, encoding at the production facility, decoding (by a STB, for example) and ultimate playout by an end consumer device each experiences an additional delay. However, the time delay Tcontrol is unacceptable from the consuming perspective as the technical director's editorial decisions will not be based on the actual live events (in real time or close thereto), but only after viewing a delayed image of the events. This results in uncertainty, and missing certain actions during the event, which then detracts from the end consumer's experience.
Thus, a live video broadcasting environment is needed that exploits virtualization techniques so that the end consumer is provided with the illusion that the live event is being produced in real time.